Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The annotations already declare readOnlyHint=true, so the description's 'Read-only' adds nothing new, and the 'GraphQL: query appointment(id)' detail is an implementation note rather than agent-relevant behavior. It says nothing about return shape, auth scope, or error behavior for a nonexistent id.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short fragments with the core action front-loaded and no filler. The trailing GraphQL line is largely waste for an agent, which keeps this from a 5.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

There is no output schema, so the description carries the burden of hinting at what comes back, and it does not. For a one-parameter read tool with annotations covering safety, it is adequate but leaves the return value and failure mode unaddressed.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and the sole parameter's schema already says 'The appointment id.' The description's 'by id' restates rather than extends that, so the high-coverage baseline of 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('Fetch') and resource ('a single appointment') and constrains it to lookup by id, which cleanly distinguishes it from the sibling healthie_list_appointments. It stops short of naming that sibling, so it is clear but not fully differentiated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: 'by id' tells the agent it needs a known identifier, and 'single' implies it is not for enumeration. No explicit when-to-use statement or reference to healthie_list_appointments as the alternative for browsing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.